As is known, microfluidic systems are being used in an increasing number of applications. However, further expansion of the uses for such microfluidic devices has been limited due to the difficulty and expense of fabrication. By way of example, Chow, U.S. Pat. No. 6,167,910 discloses a multi-layer microfluidic device and method of making the same. The microfluidic device disclosed in the Chow '910 patent includes a body structure having a plurality of substrate layers such as a bottom substrate, a middle substrate and a top substrate. The bottom substrate includes a top surface having grooves fabricated therein in any conventional manner, such as by etching or the like. Upon the mating of the top surface of the bottom substrate with the bottom surface of the middle substrate, these grooves form a channel network for the microfluidic device. Additional channel networks may be formed by the top surface of another substrate and the bottom surface of the adjacent substrate. In such manner, multi-layer channel networks may be formed within a microfluidic device. Ports may be provided in each of the substrates to interconnect the various channel networks within the microfluidic device. It is contemplated to thermally bond the substrates together in order to form an integral, microfludic device.
While the method disclosed in the Chow '910 patent is functional for its intended purpose, the method disclosed therein has significant limitations. By way of example, each of the substrates must be preformed using traditional microfabrication methods that involve etching. These traditional methods are inherently expensive due to the equipment, materials and process complexity issues required. Further, the cost of thermally bonding the substrates together in high temperature annealing ovens increases the overall cost to manufacture the microfluidic device. As such, it is highly desirable to provide a simpler and more economical method of fabricating microfluidic devices.
Therefore, it is a primary object and feature of the present invention to provide a method of fabricating a microstructure that is simple and inexpensive.
It is a further object and feature of the present invention to provide a method of fabricating a microstructure that may be performed more quickly than prior methods of fabrication.
It is a still further object and feature of the present invention to provide a method of fabricating a microstructure that allows for customization of the microstructure to be fabricated without undue additional expense.
In accordance with the present invention, a method is provided for fabricating a microstructure including a base layer having an upper surface. The method includes the step of providing a first layer having upper and lower surfaces. The lower surface of the first layer is in a spaced relationship to the upper surface of the base layer such that the lower surface of the first layer and the upper surface of the base layer define a construction cavity therebetween. The first layer has a passageway therethrough that communicates with the construction cavity. The construction cavity is filled with material and a polymerizing agent is directed towards a portion of the material within the construction cavity of outside the channel to be formed therein such that the portion of the material is polymerized. The material within the channel is flushed therefrom.
The first layer may include a fill hole therethrough to allow for the filling of the construction cavity. In addition, the passageway communicates with the channel. The passageway may be plugged to prevent material from flowing therein during filling. It is contemplated to provide a gasket about the construction cavity to maintain the material therein during filling.
A second layer may be provided having upper and lower surfaces and being in a spaced relationship to the first layer such that the lower surface of the second layer and the upper surface of the first layer define a second construction cavity therebetween. The second layer has a passageway therethrough that communicates with the second construction cavity. The second construction cavity is filled with material. A polymerizing agent is directed towards a portion of the material within the second construction cavity such that the portion of the material is polymerized. The material is flushed from the channel in the second construction cavity.
The passageway through the second layer and the passageway through the first layer are axially aligned and communicate with each other through the channel in the second construction cavity. The passageway in the first layer may be plugged to prevent the material from flowing therein during the step of filling the second construction cavity with material. Thereafter, the passageway in the first layer is cleared after a portion of the material is polymerized within the second construction cavity such that the channel in the first construction cavity and the channel in the second construction cavity communicate through the passageway in the first layer. The passageway through the second layer communicates with the upper surface of the second layer through an opening. The method of the present invention may include the additional step of closing the opening.
It is contemplated that the passageway through the first layer communicate with the channel in the first construction cavity and with the channel in the second construction cavity. The first layer includes a second passageway therethrough that communicates with the channel in the construction cavity. The passageway in the second layer communicates with the channel in the second construction cavity and with the upper surface of the second layer through a first opening. The second layer includes a second passageway therethrough that communicates with the second passageway through the first layer and with the upper surface of the second layer through a second opening. One of the openings in the second layer comprises an input and the other of the openings comprises an output to the microfluidic device.
In accordance with a further aspect of the present invention, a method is provided for forming a microstructure. The method includes the steps of providing a material in an area and directing a polymerizing agent towards a portion of the material within the area so as to polymerize the same. By way of example, the microstructure may include a base layer having an upper surface. As such, the method would include the step of providing a first layer having upper and lower surfaces. The lower surface is in a spaced relationship to the upper surface of the base layer such that the lower surface of the first layer and the upper surface of the base layer define a construction cavity therebetween. The construction cavity is filled with material and the polymerizing agent is direct towards a portion of the material within the construction cavity so as it will polymerize the same.
The polymerized material defines a first channel within the microstructure device. The material in the first channel is flushed therefrom. The step of directing the polymerizing agent towards the portion of the material includes the step of generating ultraviolet radiation with a source. The ultraviolet radiation is directed towards the portion of material to be polymerized.
It is contemplated to provide a second layer having upper and lower surfaces. The second layer is spaced from the first layer such that the lower surface of the second layer and the upper surface of the first layer define a second construction cavity therebetween. The second construction cavity is filled with the material and a portion of the material is polymerized so as to polymerize the same. The solidified material defines a second channel in the microstructure. A first passageway is provided through the first layer that communicates with the first and second channels. A second passageway is provided through the first layer that communicates with the first channel. A first passageway is provided in the second layer that communicates with the second channel and with the upper surface of the second layer through a first opening. In addition, a second passageway is provided through the second layer that communicates with the second passageway through the first layer and with the upper surface of the second layer through a second opening. One of the openings in the second layer comprises as an input and the other of the openings comprises an output to the microstructure.
In accordance with a further aspect of the present invention, a method is provided for constructing a microstructure. The method includes the steps of injecting a fluidic material into a construction cavity and directing a polymerizing agent towards a portion of the fluidic material within the construction cavity so as to polymerize the same. Thereafter, the non-polymerized, fluidic material is flushed from the construction cavity.
The polymerized material defines a channel network in the microstructure device and the non-polymerized, fluidic material is flushed from the channel network. The step of polymerizing the portion of the fluidic material includes the additional steps of generating ultraviolet radiation with a source and directing the ultraviolet radiation towards the portion of material to be polymerized. It is contemplated that the ultraviolet radiation is ultraviolet light and the ultraviolet light is directed towards the portion of material by an array of micromirrors. The method may also include the additional steps of injecting a fluidic material into a second construction cavity and directing a polymerizing agent towards a portion of the fluidic material within the second construction cavity so as to polymerize the same. Thereafter, the fluidic material is flushed from the second construction cavity.